A mobile network represented by a mobile operator network, as shown in FIG. 30, is configured by an E-UTRAN Node-B (eNodeB) X40, a Mobility Management Entity (MME) X41, a Serving Gateway (Serving GW) X42, and a Packet Data Network Gateway (PDN GW) X43 (refer to Non-Patent Document 1) An outline thereof is described below.
The eNodeB X40 is a logical channel control device that provides a logical channel to a communication terminal through wireless access, referred to as Long Term Evolution (LTE).
The MME X41 is a control device that controls a plurality of eNodeBs and Serving GWs, and is provided with a function to control a logical channel referred to as an Evolved Packet System (EPS) bearer in order to support handover between eNBs and packet communication for a communication terminal.
The Serving GW X42 is a packet forwarding device belonging to a geographical area inside which a communication terminal is present, and is provided with a function to relay a data packet forwarded between an eNodeB and the PDN GW.
The PDN GW X43 is a gateway device for providing access to a Packet Data Network (PDN) 11, and is provided with a function of generating an EPS bearer for a communication terminal via the Serving GW X42, and also of giving out an IP address in order to access the PDN 11 to the communication terminal. The PDN may be, for example, an operator network (a telecommunications carrier network) or intranet, a university campus network, a home network, or the like.
In the mobile network of FIG. 30 described above, the communication terminal X51 is connected to the eNodeB X40, and a description is given using FIG. 31, concerning a series of steps up to accessing a server X61 that is inside the PDN 11.
On linking up with the eNodeB X40, the communication terminal X51 generates the EPS bearer in order to access the PDN 11. At this time, the MME X41 and the Serving GW X42 use information referred to as Access Point Name (APN) to identify the PDN 11 that the communication terminal X51 is trying to access. This APN may be obtained by a method in which the communication terminal X51 gives notification to a communication system, or a method of downloading from a subscriber information database referred to as a Home Subscriber Server (HSS), which is omitted in FIG. 30. The PDN GW X43 gives out an IP address for accessing the PDN 11, to the communication terminal X51 at this time. As described above, when the EPS bearer is established between the communication terminal X51 and the PDN 11, a series of tunnels is generated between the communication terminal X51 and the PDN 11. The communication terminal X51 can access the server X61 present inside the PDN 11 via tunnels established in this way.
In this way, with technology of Non-Patent Document 1, in order for the communication terminal to realize access by generation of the tunnels as far as the PDN, the PDN and the communication terminal use a private IP address, and even if there is an address conflict of another PDN or communication terminal and an address space, it is possible to identify communications of each thereof, and to provide respective PDN access.
Non-Patent Document 2 is a specification of technology known as OpenFlow. In OpenFlow, communication is taken as end-to-end flow, and path control, recovery from failure, load balancing, and optimization are performed in flow units. An OpenFlow switch functioning as a forwarding node is provided with a secure channel for communication with an OpenFlow controller and operates according to a flow table in which appropriate addition or rewriting is instructed by an OpenFlow controller. In the flow table, sets (processing rules) of rules (FlowKey, matching key) for collation with packet headers, actions (Action) defining processing content, and flow statistical information (Stats), are defined for each flow (refer to FIG. 32).
For example, when an OpenFlow switch receives a first packet, an entry is searched for, that has a rule (FlowKey) matching header information of the received packet, from the flow table. As a result of the search, in a case where an entry matching the received packet is found, the OpenFlow switch implements processing content described in an action field of the entry, for the received packet. On the other hand, as a result of the search, in a case where an entry matching the received packet is not found, the OpenFlow switch forwards the received packet to the OpenFlow controller via a secure to request determination of a path of the packet based on source and destination of the received packet, receives a processing rule (flow entry) for realizing this, and updates the flow table. According to the above description, forwarding of the packet belonging to the flow is realized.
[Non-Patent Document 1]
3GPP TS 23.401 ver. 9.3.0. “General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access”, [search conducted Mar. 8, 2010] Internet URL: <http://www.3gpp.org/ftp/Specs/archive/23_series/23.401/23401-930.zip>
[Non-Patent Document 2]
“OpenFlow Switch Specification” Version 1.0.0. (Wire Protocol 0x01), [search conducted Mar. 8, 2010] Internet URL: <http://www.openflowswitch.org/documents/openflow-spec-v1.0.0.pdf>